An optical emitting circuit can be incorporated, for example, into electronic devices such as tablets or cellular mobile telephones for applications based on the use of the principle of indirect time-of-flight (iToF) or of light fidelity (LiFi).
In general, an optical emitting circuit able to apply the indirect time-of-flight principle emits optical pulses, for example, infrared optical radiation in the form of a square wave, towards a scene. Two-dimensional or even three-dimensional elements of the scene return these optical pulses to a sensor of the circuit, which comprises an array of detecting pixels. The shifts in the phase of the optical pulses between the emission and reception of these pulses are measured by the sensor so as to determine indirectly the time-of-flight of these pulses and the distances between the elements of the scene and the circuit, thereby advantageously allowing the bulk and cost of the circuit to be decreased while preserving a reasonable precision with respect to an equivalent “direct time-of-flight” sensor.
However, there is a need to carry out such a phase-shift measurement for sinusoidal optical signals, as this is advantageously simpler than for square wave optical signals.